Two types of road barriers are known, which differ from each other essentially in the structure and construction material. A first type of barrier, also called “guard-rail”, is made of metal and comprises a plurality of vertical uprights, separated from each other with a constant pitch, made with open section profiles, for example U-shaped or similar, fixed into the ground, onto which longitudinal elements or longitudinal profiles, also with an open section and made of undulated sheet, are attached.
The second type of barrier, called “New Jersey”, consists of a plurality of modules, consisting of concrete or metal blocks, which are coupled with each other laterally and anchored to the roadway.
The advantages of the guard-rail barriers are essentially due to the greater structural elasticity that, in the event of an accident, allows high shock absorption and an adequate deformation of the barrier, generally limiting the consequences for the people involved. However, in the event of a violent impact, this type of barrier does not guarantee an adequate containment, so that the vehicle can knock down the barrier and go off the road, or leap-frog the barrier and finish up on the opposite carriageway. Moreover, the open profile sheet that forms the longitudinal elements constitutes a cutting element, which can turn out to be very dangerous for the people involved in the accident.
The “New Jersey” barrier has a greater resistance to shock, and therefore it is more difficult to knock down; moreover, it defines an inclined surface at the base, converging towards the roadway which, if mounted by the tires of a vehicle, encourages the latter to return inside the carriageway, preventing it from knocking into the barrier and from leap-frogging it. This inclined surface is, however, very short and very near the vertical part of the barrier so that, even if it can prevent the collision, it cannot prevent the parts of the vehicle protruding from the sides, for example the side mirrors, from scraping the barrier.
The rigidity of the “New Jersey” barrier, moreover, especially if it is made of concrete, in the case of a collision generally causes more damage both to vehicles and also, consequently, to the people involved.
Furthermore, when it is made of metal, the “New Jersey” barrier has problems of transport and of construction, because it is difficult to make a large size box-like structure.
A further limitation common to these two types of road barrier is when, for example due to successive applications of asphalt, or the installation of soundproofing panels, it is necessary to increase the height of the barrier with respect to the roadway. This operation, in fact, can be carried out only by replacing particular components, or by complex operations of joining or anchoring new elements to the existing barrier, with considerable expense and long execution times.
Another shortcoming of conventional barriers concerns the maintenance operations that have to be periodically carried out to restore the barrier after even only small collisions. Moreover, especially in the case of guard-rail barriers, there is the problem of the growth of grass between one upright and the other, which makes frequent grass-cutting operations necessary; such operations are difficult due to the presence of the uprights, which make it difficult to cut round them, and also because the zones located under the longitudinal elements can only be reached with difficulty with conventional cutting instruments.
The difficulties connected to the operations to modify and maintain conventional road barriers, and the frequency thereof, entail not only a waste of economic and human resources, but also considerable and prolonged problems to the traffic in those sections of road where they have to be carried out.
Document DE-U-201 13 347 discloses a road barrier according to the preamble of independent claim 1.
The present Applicant has devised and embodied this invention to overcome the shortcomings of the state of the art, and to obtain further advantages.